1. The problem statement, all variables and given/known data http://i.imgur.com/Ypqcw19.png 2. Relevant equations N/A 3. The attempt at a solution Since the reaction involves the breaking of bonds in MCO3, I assume we are looking at coulomb interactions. I'd think the answer is D) BaCO3 because all the options have a 2+ charge, but barium has the largest radius.